Abstract: As a security risk in the field of payment, the double spend attack has brought a serious impact on the normal operation of the blockchain system. Aiming at 51% double spend attacks with strong destructive force in double spend attacks, an evolutionary game model of 51% double spend attacks in blockchain is built to reveal the dynamic evolution trend of node strategies, and the probability of 51% double spend attacks is predicted by deducing evolutionary stability strategies. At the same time, transaction price and transaction fee are taken as two important variables in evolutionary game model to explore the influence of different values of this variable on game results. Simulation experiments verify the effectiveness of the above model, and finally the risk prevention and control strategy and suggestions are put forward from the two aspects of transaction fee and transaction price.

Key words: blockchain, 51% double spend attack, evolutionary game, transaction fee, transaction price

摘要： 双花攻击作为支付领域的一种安全隐患，给区块链系统的正常运行带来了严重影响。针对双花攻击中破坏力较强的51%双花攻击，构建了区块链中51%双花攻击的进化博弈模型，揭示了节点策略的动态演化趋势，并通过推导进化稳定策略，预测双花攻击出现的概率。同时把交易价格和交易费用作为进化博弈模型中的两个重要变量，探究该变量的不同取值对博弈结果的影响规律。仿真实验验证了上述模型的有效性，最后从交易费用和交易价格两个方面提出了51%双花攻击风险防控的策略和建议。

关键词: 区块链, 51%双花攻击, 进化博弈, 交易费用, 交易价格